1. Field of the Invention
The invention relates to an assembly of exhaust pipes for an automobile vehicle.
2. Description of the Related Art
The typical prior art exhaust system includes at least one manifold for collecting exhaust gas produced by the cylinders of an internal combustion engine. An exhaust pipe delivers the collected gas from the manifold to a catalytic converter where certain objectionable pollutants are converted into a less objectionable form. Another pipe extends from the catalytic converter to a muffler that attenuates noise associated with the flowing exhaust gas. At least one tail pipe then extends from the muffler to a location on the vehicle where the exhaust gas can be emitted safely.
The exhaust gas heats the components of the exhausts system, and hence requires the components of the exhaust system to be located and routed to ensure sufficient clearance from parts of the vehicle that can be damaged by heat. The exhaust pipe also must be routed to locations with sufficient space to accommodate the catalytic converter and the muffler. These controls on the location of the exhaust system components generally results in a very circuitous alignment of the exhaust pipes.
Exhaust system routing is particularly complex for V-engines, such as a V-6 or a V-8, and especially a V-engine that is mounted transversely in vehicle. The cylinders of V-engine are disposed in two angularly aligned planes and emit exhaust gases from opposite respective sides of the engine. As a result, two separate exhaust pipes must extend from spaced-apart manifolds on the V-engine, such as a front manifold and a rear manifold on a transversely mounted V-engine. A vehicle with a V-engine conceivably could have two separate exhaust systems with independent catalytic converters and mufflers. However, these systems are costly and can further complicate efforts to locate the catalytic converters and mufflers. As a result, most vehicles with V-engines have the respective exhaust pipes converge and join at a location upstream from the muffler.
The noise produced by an internal combustion engine is actually a series of repeating noises corresponding respectively to the sequential controlled explosions taking place in the cylinders of the engine. Engineers examine the loudness and frequency of noise resulting from these explosions and design an appropriate array of tubes and chambers in a muffler for attenuating the pattern of noise observed in a particular vehicle. The task of designing a muffler is more complicated if the noise from the respective explosions does not define a uniform and repetitive pattern approaching the muffler. A non-uniform pattern may cause sound waves from one explosion to partly overlap sound waves from another explosion. The additive effect of these overlapping noise patterns can complicate the acoustical tuning of the exhaust system.
Most properly tuned engines will produce uniform firing of the cylinders, and hence has the potential to direct a uniform series of noise patterns to the muffler for attenuation. However, the V-engines with a single muffler often have different exhaust gas travel lengths between the respective manifolds and the muffler. Engineers can try to route the exhaust types for a V-engine to achieve substantially equal lengths between the respective manifolds and the point where the exhaust pipes converge. However, the engine compartment of a typical vehicle is extremely crowded and engineers generally do not have the luxury of routing the exhaust pipes from a V-engine in a way that will ensure substantially equal lengths.
U.S. Pat. No. 5,473,891 is assigned to the assignee of the subject invention and teaches the use of a stamped-formed connector in an effort to equalize the lengths of two exhaust pipes. More particularly, the connector of U.S. Pat. No. 5,473,891 has three plates stamped-formed to define an array of channels. The plates are secured in face-to-face relationship with one another so that the channels define an array of tube-like passages between adjacent plates. The passages are disposed to define two inlets for connection with the respective exhaust pipes. The passages join at a selected location in the connector and extend to a single outlet. The array of channels in the plates is formed so that one of the passages exceeds the length of the other passage by a difference between the respective lengths of the exhaust pipes. As a result, the stamped-formed connector will equalize the exhaust gas travel distance between the respective manifolds and the muffler.
Stamped-formed exhaust components can achieve several cost and manufacturing efficiencies and can be designed to fit into the limited available space in the engine compartment and beneath the vehicle. However, the design options available with the stamped-form technology of U.S. Pat. No. 5,473,891 cannot easily accommodate significant differences in the lengths of two exhaust pipes. More particularly, there generally is not a sufficient volume of space available in the engine compartment or beneath the vehicle for one array of channels in a stamp formed connector to make up a significant difference in the lengths of two exhaust pipes. Furthermore, a very circuitous arrangement of channels in a stamped-formed connector could create a back-pressure with an adverse effect on engine performance and fuel efficiency.
Accordingly, it is an object of the subject invention to provide an assembly for equalizing the exhaust gas travel lengths of two exhaust pipes.
Another object of the subject invention is to provide an assembly that enables the exhaust gas travel length to be equalized without utilizing a large volume of space in the engine compartment or under the vehicle.
It is a further object of the subject invention is to provide an assembly for equalizing the effective length of two exhaust pipes without a circuitous array of pipes that could increase back pressure in the flowing exhaust gas.